Surgical adhesive compositions for tissue are well known as evidenced, for example, by U.S. Pat. No. 5,385,606 (the entire content of which is expressly incorporated hereinto by reference). In general, such surgical adhesives are achieved by combining a two part system typically comprised of a water soluble proteinaceous material (e.g., albumin, particularly bovine or human serum albumin), and a di- or polyaldehyde (e.g., glutaraldehyde) in appropriate amounts, and allowing the combined mixture to react in situ on the tissue surface or surfaces to be bonded. In this manner, sutureless (or minimally sutured) repairs of tissue wounds, perforations, tears and the like may be achieved.
Some tissue wounds, tears, and/or perforations are too large and/or complex to allow for the in situ reaction and repair by conventional biocompatible surgical adhesives. Thus, it would be highly desirable if pre-formed solid self-supporting, shaped, three-dimensional biocompatible materials possessing sufficient physical strength properties were provided which could be implanted in vivo and thereby enable physicians to repair tissue wounds, tears and/or perforations that are too large and/or complex to allow repair by conventional bioadhesives. It is towards fulfilling such needs that the present invention is directed.
Broadly, the present invention is embodied in self-supporting, shaped, three-dimensional cross-linked proteinaceous biopolymeric materials that may be implanted in vivo, and in the methods of making such materials. Most preferably, the biopolymeric materials of this invention are shaped to allow implantation in vivo. Specifically, according to one preferred embodiment of this invention, the biopolymeric materials of this invention may be cast onto suitable smooth casting surfaces, such as, for example, surfaces formed from stainless steel, aluminum, glass or polymeric (e.g., Lexan® polycarbonate) to make sheets of desired thickness.
According to one preferred embodiment of the invention, the shaped biopolymeric materials may integrally include reinforcing media, such as biocompatible fibrous or particulate materials. If used, the fibrous reinforcing media may be in the form of individual fibers, filaments, rovings and/or yarns embedded into the biopolymeric materials. Alternatively (or additionally), the fibrous reinforcing media may be in the form of woven or non-woven fabric or web structures which are embedded physically within the biopolymeric materials. The reinforcing media may also be in the form of particulate media that may be used alone or in combination with the fibrous reinforcing media.
The biomaterial structures of the present invention may be subjected to a variety of aftertreatments in order to achieve desired physical and/or chemical properties. For example, the tensile strength, flexibility, transparency, texture, biological (e.g., protease) resistance, chemical resistance and the like, may be engineered by virtue of such aftertreatments to suit particular end-use applications. In this regard, the aftertreatments may include, for example, bringing the biomaterial structure into contact with a desired treatment liquid, such as water or an organic liquid (e.g., alcohol, urea or glutaraldehyde solutions). Aqueous solutions of a salt (e.g., sodium chloride) have also been found to affect the biomaterial structure's resistance to proteolysis.
The biomaterial structures of the present invention may also be rendered porous, if desired. Specifically, a dissolvable particulate medium (e.g., calcium carbonate) may be dispersed throughout the biomaterial structure as briefly described above. The particulate-laden biomaterial structure may then be brought into contact with a suitable solvent for the particulate medium so as to dissolve a sufficient amount of the same to render the biomaterial structure porous. For example, when employing calcium carbonate as the particulate medium, the biomaterial structure may be brought into contact with hydrochloric acid sufficient to dissolve an amount of the calcium carbonate and render the structure porous. That is, pores will remain in the biomaterial structure following dissolution of the particulate medium.
These and other aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.